Project Summary/Abstract The proposed R34 study will integrate existing tools for use with JJ populations and examine the feasibility, acceptability, and preliminary efficacy of a caregiver-youth intervention aimed at increasing SU treatment initiation. The Family Assessment, Motivation, and Linkage Intervention (FAMLI) is an adaptive intervention that incorporates three evidence-based components: 1) assessment of motivation and linkage-related barriers with personalized feedback, 2) Mapping-Enhanced Counseling (MEC) for improving readiness for change and interpersonal communication, and 3) Active Linkage (AL) for addressing logistical barriers to service initiation. Using a Sequential Multiple Assignment Randomized Trial (SMART), 80 youth-caregiver dyads will be randomly assigned to receive an initial dose (2, 1-hr sessions) of either MEC or AL. After 30 days, participants will be classified as Responders (1 or more services initiated) or Non-responders (no service initiation). Responders will receive encouragement to continue SU services, but no further MEC or AL; Non-responders will be randomized to one of two intervening interventions: an additional dose (2, 1-hr sessions) of the initial intervention (MEC or AL) or a different dose (2, 1-hr sessions of the other). The specific aims are to 1) integrate and adapt appropriate evidence-based intervention components as a dyadic intervention approach for JJ youth and caregivers; 2) test the feasibility, acceptability, and optimal configuration of the dyadic intervention components and the protocol used to evaluate effectiveness (including feasibility of recruitment, implementation, measurement); and 3) preliminarily explore a) whether an initial dose of MEC or AL is sufficient for promoting early initiation, b) whether an additional dose of MEC or AL or a change in dose is more effective for Non-responders, and c) which component sequence is most effective for Non-responders. Primary outcomes include youth (initiation of assessment or counseling; counseling attendance) and caregiver (attendance at assessment, first counseling, and/or family sessions) measures. Secondary outcomes include youth and caregiver attitudes (problem recognition, desire for help), normative beliefs (SU norms), perceived control (stressors and obstacles), and youth SU (self-report corroborated by UA results). The proposed study addresses the sizeable gap in service receipt among JJ youth by addressing family engagement, and focuses on improving motivation to change, linkage to services, and treatment engagement.